The embodiments described herein relate generally to power equipment protection devices and, more particularly, to arc mitigation systems for use in channeling exhaust gases and pressure away from a location of arc generation.
Known electric power circuits and switchgear generally have conductors that are separated by a distance with insulation, such as air, or gas or solid dielectrics. However, if the conductors are positioned too closely together, or if a voltage between the conductors exceeds the dielectic strength of the insulation between the conductors, an arc flash can occur. Arc flash also can occur in case of aging insulations, rodents, and improper maintenance procedures. The insulation between the conductors can become ionized, which makes the insulation conductive and enables arc formation. An arc flash causes rapid release of energy due to a fault between phase conductors, between a phase conductor and a neutral conductor, or between a phase conductor and a ground point. Arc flash temperatures can reach or exceed 20,000° C., which can vaporize the adjacent conductors and burn through the sheets of adjacent equipment panels. In addition, an arc fault is associated with release significant amount of energy in the form of heat, intense light, pressure waves, and/or sound waves due to which heavy damage to the conductors and adjacent equipment can occur. In general fault current and energy associated with an arc event are lower compared to the fault current and energy associated with bolted short circuit fault. Due to inherent delay between the relay closure and the upstream circuit breaker clearing the arc fault, huge damage can occur at fault location. Circuit breaker can be operated using the faster tripping mechanism to reduce the damage. Even with this feature the damage cannot be minimized.
At least some known systems use an arc mitigation system to safely divert fault energy from the location of an arc flash to a safe zone. The arc mitigation system has a containment device/chamber that often includes electrodes or conductors that are separated by a distance and have a sufficient dielectric strength between them to not to cause arc flash without external aid. A plasma generating device is included within the arc containment chamber. When the arc flash event is detected, the plasma device emits ablative plasma towards the electrodes. The ablative plasma reduces electrical impedance between the electrodes, and an electrical arc may be formed between the electrodes. The electrical arc diverts energy from the first arc flash zone to the arc chamber until the arc flash is abated or extinguished. In order to safely transfer and contain energy away from the electrical arc, the arc containment device should not pass excessive current in or through the ground path. The deposition of charged particles from the arc event on the grounded parts of arc mitigation system, generally causes the current flow through ground path. To avoid excessive current flow through ground, additional components such as charge collectors and/or a coating such as epoxy and/or ceramic are used which make the production process complex and also increases the cost.